Recently, the progress in the field of semiconductor manufacturing technology has been striking, and in particular, the demand for ultrafine structures and high levels of integration has become pressing; however, in conjunction with this, the necessity has arisen to maintain the environment of the manufacturing device in a state of ultrahigh purity (that is to say, purity on the level of parts per trillion). As a result, in the case in which sample gas of common gas (for example, argon gas, nitrogen gas, or the like) or special gas (for example, silane gas) having the necessary degree of ultrahigh purity for the manufacture of silicon substrates is supplied through a pipe system which serves as a gas flow path, it is necessary to determine the amount of impurities such as moisture and the like which are contained in the sample gas, on the level of parts per trillion.
Measuring methods for determining the impurity adsorption amount in common gases (argon gas, nitrogen gas, and the like), which were commonly employed, include the connection of a trace gas analyzer (atmospheric pressure ionization mass spectrometer) to the pipe end of a sample pipe through which this common gas is caused to flow, and measuring the amount of impurities flowing out of the pipe end of this sample pipe.
However, in the case in which such a special gas had corrosive or flammable characteristics, damage was done to the measurement system, or the handling of this gas presented difficulties, so that it was impossible to employ the measurement method which was used in the case of common gases. Accordingly, in the case of such special gasses, there was no method for confirming the relationship between impurity amounts and gas flow amounts, and the like, so that, in other words, only a rough estimate could be made, and this was insufficient for the purposes of the manufacture of semiconductors having the ultrafine structures discussed above.
The present invention solves the problems which were present in the conventional technology discussed above, and has as an object thereof to provide a device which is capable of conducting, easily, and on a level of parts per trillion, the measurement of impurity amounts and the like contained in special gasses which present difficulties in handling.